To add leading zeros I prefer the following:
<?php
// Add leading zeros
$bin = sprintf( "%08d", decbin( 26 )); // "00011010"
?>
(PHP 4, PHP 5, PHP 7)
decbin — Decimal to binary
$number
)
Returns a string containing a binary representation of the given
number argument.
numberDecimal value to convert
positive number |
negative number |
return value |
|---|---|---|
| 0 | 0 | |
| 1 | 1 | |
| 2 | 10 | |
| ... normal progression ... | ||
| 2147483646 | 1111111111111111111111111111110 | |
| 2147483647 (largest signed integer) | 1111111111111111111111111111111 (31 1's) | |
| 2147483648 | -2147483648 | 10000000000000000000000000000000 |
| ... normal progression ... | ||
| 4294967294 | -2 | 11111111111111111111111111111110 |
| 4294967295 (largest unsigned integer) | -1 | 11111111111111111111111111111111 (32 1's) |
positive number |
negative number |
return value |
|---|---|---|
| 0 | 0 | |
| 1 | 1 | |
| 2 | 10 | |
| ... normal progression ... | ||
| 9223372036854775806 | 111111111111111111111111111111111111111111111111111111111111110 | |
| 9223372036854775807 (largest signed integer) | 111111111111111111111111111111111111111111111111111111111111111 (63 1's) | |
| -9223372036854775808 | 1000000000000000000000000000000000000000000000000000000000000000 | |
| ... normal progression ... | ||
| -2 | 1111111111111111111111111111111111111111111111111111111111111110 | |
| -1 | 1111111111111111111111111111111111111111111111111111111111111111 (64 1's) | |
Binary string representation of number
Example #1 decbin() example
<?php
echo decbin(12) . "\n";
echo decbin(26);
?>
The above example will output:
1100 11010
To add leading zeros I prefer the following:
<?php
// Add leading zeros
$bin = sprintf( "%08d", decbin( 26 )); // "00011010"
?>
Just an example:
If you convert 26 to bin you'll get 11010, which is 5 chars long. If you need the full 8-bit value use this:
$bin = decbin(26);
$bin = substr("00000000",0,8 - strlen($bin)) . $bin;
This will convert 11010 to 00011010.
A fast function to convert a binary string to a bit sequence
<?php
function BinString2BitSequence($mystring) {
$mybitseq = "";
$end = strlen($mystring);
for($i = 0 ; $i < $end; $i++){
$mybyte = decbin(ord($mystring[$i])); // convert char to bit string
$mybitseq .= substr("00000000",0,8 - strlen($mybyte)) . $mybyte; // 8 bit packed
}
return $mybitseq;
}
echo BinString2BitSequence("ABCDEF"); // OUTPUT=010000010100001001000011010001000100010101000110
?>
If you want leading zeros use php built-in features instead of custom functions
<?php
printf('%08b', $decimal);
?>
>> printf('%08b', E_NOTICE)
>> 00001000
A little useful little function that returns a binary string with leading 0s:
function d2b($n) {
return str_pad(decbin($n), 16, "0", STR_PAD_LEFT);
}
// example:
echo d2b(E_ALL);
echo d2b(E_ALL | E_STRICT);
echo d2b(0xAA55);
echo d2b(5);
Output:
0111011111111111
0111111111111111
1010101001010101
0000000000000101
Decimal to Binary conversion using the BCMath extension.
<?php
function BCDec2Bin($Input='') {
$Output='';
if(preg_match("/^\d+$/",$Input)) {
while($Input!='0') {
$Output.=chr(48+($Input{strlen($Input)-1}%2));
$Input=BCDiv($Input,'2');
}
$Output=strrev($Output);
}
return(($Output!='')?$Output:'0');
}
?>
This will simply convert from Base-10 to Base-2 using BCMath (arbitrary precision calculation).
See also: my 'BCBin2Dec' function on the 'bindec' document.
Enjoy,
Nitrogen.
Another larger-than-31-bit function.
Works for very large numbers, but at the expense of perfect bit-precision as the size increases (I noticed rounding errors past 16 or so decimal places) so use with caution, and only when decbin() won't cut it.
function Dec2Bin($number) {
while ($number >= 256) {
$bytes[] = (($number / 256) - (floor($number / 256))) * 256;
$number = floor($number / 256);
}
$bytes[] = $number;
for ($i=0;$i<count($bytes);$i++) {
$binstring = (($i == count($bytes) - 1) ? decbin($bytes[$i]) : str_pad(decbin($bytes[$i]), 8, "0", STR_PAD_LEFT)).$binstring;
}
return $binstring;
}
HERE you can convert 64bit instead of 32bit with the standard decbin
<?
function bigdecbin($dec,$doublewords=1) {
$erg = "";
do {
$rest = $dec%2147483648;
if ($rest<0) $rest+=2147483648;
$erg = str_pad(decbin($rest),31,"0",STR_PAD_LEFT).$erg;
$dec = ($dec-$rest)/2147483648;
} while (($dec>0)&&(!($dec<1)));
return str_pad($erg,$doublewords*31,"0",STR_PAD_LEFT);
}
echo "<pre>";
for ($i=1.5*2147483647.0-10;$i<1.5*2147483647.0+10;$i++) {
echo "DEC:".$i." BIN:".bigdecbin($i,2)."<br>";
}
echo "</pre>";
?>
hi folks, i struggled for a day to get a big decimal number converted into binary, on the windows platform.
finally with bcmath functions this is what worked for me.
function bc_convert2bin($string) {
//got it to work with bcmath functions, works for 64 bit on 32 bit windows machine
$finished=0;
$base=2;
$bin_nr='';
if(preg_match("/[^0-9]/", $string)) {
for($i=0; $string!=chr($i); $i++) {
$dec_nr=$i;
}
} else {
$dec_nr=$string;
}
//while( $dec_nr>$base ) {
while( bccomp($dec_nr,$base) == 1 ) {
//$base=$base*2;
$base=bcmul($base,'2');
//if($base>$dec_nr) {
if( bccomp($base,$dec_nr) == 1 ) {
//$base=$base/2;
$base=bcdiv($base,'2');
break;
}
}
while(!$finished) {
//if(($dec_nr-$base)>0) {
if( bccomp( bcsub($dec_nr,$base) , 0) == 1 ) {
//$dec_nr=$dec_nr-$base;
$dec_nr=bcsub($dec_nr,$base);
$bin_nr.=1;
//$base=$base/2;
$base=bcdiv($base,'2');
//} elseif(($dec_nr-$base)<0) {
} elseif( bccomp( bcsub($dec_nr,$base) , 0) == -1 ) {
$bin_nr.=0;
//$base=$base/2;
$base=bcdiv($base,'2');
//} elseif(($dec_nr-$base)==0) {
} elseif( bccomp( bcsub($dec_nr,$base) , 0) == 0 ) {
$bin_nr.=1;
$finished=1;
//while($base>1) {
while( bccomp($base,1) == 1 ) {
$bin_nr.=0;
//$base=$base/2;
$base=bcdiv($base,'2');
}
}
}
return $bin_nr;
}
base_convert( base_convert('100001000100000000010001001000
0100100000001111111111111111111',2,10),10,2);
return
'1000010001000000000100010010000
100100000010000000000000000000'
this function doesn't work
<?php
Print bindecValues("1023");
function bindecValues($decimal, $reverse=false, $inverse=false) {
/*
1. This function takes a decimal, converts it to binary and returns the
decimal values of each individual binary value (a 1) in the binary string.
You can use larger decimal values if you pass them to the function as a string!
2. The second optional parameter reverses the output.
3. The third optional parameter inverses the binary string, eg 101 becomes 010.
-- darkshad3 at yahoo dot com
*/
$bin = decbin($decimal);
if ($inverse) {
$bin = str_replace("0", "x", $bin);
$bin = str_replace("1", "0", $bin);
$bin = str_replace("x", "1", $bin);
}
$total = strlen($bin);
$stock = array();
for ($i = 0; $i < $total; $i++) {
if ($bin{$i} != 0) {
$bin_2 = str_pad($bin{$i}, $total - $i, 0);
array_push($stock, bindec($bin_2));
}
}
$reverse ? rsort($stock):sort($stock);
return implode(", ", $stock);
}
?>
The printed result is : 1, 2, 4, 8, 16, 32, 64, 128, 256, 512
This is my System:
You can convert a decimal number to a number system you want, like the binary system.
<?php
function Dec2oSys($numberDec, $SysNum)
{
if($numberDec != 0)
{
$numberOSys = "";
for (; $numberDec > 0;) {
$numberDecBefore = $numberDec;
$numberDec = $numberDec / $SysNum;
$pos = strpos($numberDec, '.');
if($pos != false)
{
$numberDec = floor($numberDec);
$numberOSys .= $numberDecBefore - floor($numberDec) * $SysNum;
$rest = $numberDecBefore - floor($numberDec) * $SysNum;
}
else
{
$numberOSys .= "0";
$rest = 0;
}
print $numberDec."; Rest:".$rest."<br/>";
}
}
else
{
$numberOSys = "0";
}
return strrev($numberOSys);
}
print Dec2oSys(100, 2);
?>
I think this is the best function. Is almost endlessy (till 2^50 or something)
<?php
function bin($int)
{
$i = 0;
$binair = "";
while($int >= pow(2,$i))
{
$i++;
}
if($i != 0)
{
$i = $i-1; //max i
}
while($i >= 0)
{
if($int - pow(2,$i) < 0)
{
$binair = "0".$binair;
}else{
$binair = "1".$binair;
$int = $int - pow(2,$i);
}
$i--;
}
return $binair;
}
$getal = $_GET['getal'];
echo bin($getal);
?>
Careful trying binary-wise tests with integers:
# FFFFFFFF
command: php -r 'print(decbin(4294967295)."\n");'
result: 11111111111111111111111111111111
# C3E9CAC8
command: php -r 'print(decbin(3286878920)."\n");'
result: 11000011111010011100101011001000
# regardless of specifying "(int)", using bitwise AND:
command: php -r 'print((int)(3286878920 & 4294967295)."\n");'
result: -1008088376 (int)
# now the expected result will happen (guess the performance impact)
command: php -r 'print(bindec(decbin((3286878920 & 4294967295)))."\n");'
result: 3286878920 (float)
additional note: if you "bitwise and" some random bits with a sequence of 1-bit of the same length, the expected result is the same "random bits sequence" unchanged. If you want to keep this in the integer world for faster comparisons, you risk messing your result for the signed integer size limitation. The maximum value you can use for the desired result is (7FFFFFFF -- or integer 2147483647), half of the maximum 'unsigned' integer 32-bit(platform-dependent) value.